It's not a we-figured-it-out moment, but it may be a clue. Scientists have discovered that two highly common herpes viruses tend to be present in an "increased" way in the brains of people who suffered from Alzheimer's, according to a study published Thursday in Neuron of nearly 1,000 postmortem brains. NPR reports the study also found HHV-6 and HHV-7 may "put gas on the flame," as study author Joel Dudley puts it, meaning the viruses' presence could be speeding up the progress of the disease. Now, the word of caution, from National Institute on Aging director Dr. Richard Hodes: "The data are very provocative, but fall short of showing a direct causal role. If viral infections are playing a part, they are not the sole actor."
Dudley elaborates on that point, saying the presence of the viruses in the brain doesn't trigger Alzheimer's, but something—which isn't yet known—may be waking up the viruses and causing them to start replicating. The finding does suggest at least one course of action, which Hodes says the institute will be testing: dosing people who have high herpes levels in the brain with antiviral drugs. Live Science notes that "it may sound startling to learn that there are strains of herpes in the brain," but it really isn't. Lead study author Dr. Benjamin Readhead says nearly one of every two brain tissues analyzed had the viruses; it's just that the Alzheimer's brains had up to twice as much. The HHV-6 and HHV-7 strains don't typically cause issues beyond a skin rash called roseola that little kids can experience. (Read more Alzheimer's Disease stories.)